1. Field of the Invention
The invention relates to a method and device for generating hydrogen from a powder metal hydride and water.
2. Description of Related Art
Fuel cells are seen as having great promise for providing energy in the future in an ecologically friendly manner. Portable power systems and vehicles using fuel cells are of particular interest.
Fuel cells can use a variety of fuels, including fossil fuels and their derivatives, and hydrogen. Hydrogen is seen as having great promise due to its renewability and minimal byproducts. An infrastructure of hydrogen refueling depots, however, is not in place to service fuel cell vehicles using hydrogen as fuel. Researchers are therefore looking at ways of generating hydrogen for the fuel cell on an as-needed basis.
The generation of hydrogen through the reaction of benign compounds (i.e. compounds that are easy to store safely) has been the subject of extensive research. One such reaction involves the introduction of a slurry of water and a metal hydride such as sodium borohydride to a catalyst, resulting in the production of hydrogen. This process, while effective, has certain drawbacks. The slurry is heavy, having a poor specific energy density due to the excess of water necessary to keep the slurry in a manageable fluid form. Solids also have a tendency to precipitate out of the slurry, making for a non-homogeneous mixture, inconsistent reaction with the catalyst, and clogging of the equipment. Other disadvantages to this arrangement include the need for caustic additives to stabilize the hydrogen in the water-hydride mixture, and poor heat management of the system.
It would be advantageous to refine the water-hydride type of hydrogen generation system to overcome these disadvantages, providing a fuel with greater stability, better water utilization and heat management, and a higher specific energy density.